Disc cartridge

ABSTRACT

A disc cartridge including a cartridge body formed with an aperture for exposing at least a part of the signal recording area of an accommodated disc, and a shutter member slidably mounted on the cartridge body for opening or closing the aperture, is disclosed. The cartridge body is provided with a shutter opening groove extending along the sliding direction of the shutter member which is parallel to the direction of insertion of the disc cartridge into a recording and/or reproducing apparatus adapted for recording and/or reproducing information signals on or from the disc, and a mistaken insertion inhibiting groove extending parallel to the shutter opening groove and having a length shorter than that of the shutter opening groove. Mistaken insertion of the disc cartridge may be inhibited by mistaken insertion inhibiting pins provided in the recording and/or reproducing apparatus for mating with each of these grooves.

This is a continuation of application Ser. No. 07/821,991 filed on Jan.16, 1992, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a disc cartridge having accommodated therein adisc on which predetermined information signals are recordable, or havebeen recorded, such as a magneto-optical disc or an optical disc.

2. Description of Related Art

There has previously been proposed a disc for recording and/orreproducing information signals, such as a magneto-optical disc or anoptical disc. This disc is comprised of a disc-shaped base plate and arecording layer formed on at least one major surface of the base plate.The central portion of the disc is formed as a clamping portion which isretained by a disc driving unit of a recording and/or reproducingapparatus adapted for recording and/or reproducing information signalson or from the disc. The portion of the disc lying around the clampingportion is reserved as a signal recording area on or from which theinformation signals are written or read.

Referring to FIGS. 1 and 2, there has hitherto been proposed a disccartridge comprised of a cartridge body 102 and a shutter member 104which is accommodated within the cartridge body for preventingdeposition of dust and dirt on a disc 101 or injuries thereto due tocontact especially with hands or fingers as well as for facilitatinghandling of the disc 101. The disc 101 accommodated within the cartridgebody 102 may be rotated therein by disc rotating means. Referring toFIG. 2, the major surface of the cartridge body 102 is formed with anaperture 103 by means of which at least a part of the signal recordingsurface of the disc may be exposed to outside ac ross its inner andouter peripheries. The information signals may be recorded and/orreproduced on or from the signal recording area by means of the discrecording and/or reproducing apparatus through the aperture 103.

The disc cartridge is provided with a shutter member 104 for closing theaperture 103 during non-use the disc cartridge as shown in FIG. 1 forprotecting the disc 101 by preventing intrusion of dust and dirt intothe inside of the cartridge body 102. The shutter member 104 is providedwith a shutter portion 105 of a size large enough to close the aperture103. The shutter portion 105 is formed with a through-hole 106corresponding in size and shape to the aperture 103. The shutter member104 is mounted for sliding along a lateral side of the cartridge body102 by having its proximal end face 108 supported by a correspondinglateral side of the cartridge body 102. The shutter member 104 issupported for sliding between a first position of closing the aperture103 by the shutter portion 105 as shown in FIG. 1 and a second positionof opening the aperture 103 with the through-hole 106 in register withthe aperture 103 as shown in FIG. 2.

Meanwhile, the shutter member 104 is constituted by bending asubstantially rectangular metallic plate. The shutter member 104 mayalso be formed by bending a plate of synthetic resin or by integralmolding of synthetic resin.

A recess 107 for guiding the shutter portion 105 is formed on the majorsurface of the cartridge body 102 in an area thereof corresponding tothe travel passage of the shutter portion 105. The recess 107 is of adepth corresponding to the thickness of the shutter portion 105. Thusthe upper surface of the shutter portion 105 is substantially flush withthe major surface of the cartridge body 102 for the entire slidingstroke of the shutter member with respect to the cartridge body 102.

When loaded on the disc recording and/or reproducing apparatus, the disccartridge is introduced at an entrance opening provided in the discrecording and/or reproducing apparatus with a direction normal to thesliding direction of the shutter member 104 as the inserting directionby an arrow d in FIG. 1.

At this time, the shutter member 104 is slid by a shutter member openingdevice, not shown, provided in the recording and/or reproducingapparatus, in a direction of opening the aperture 103, as shown by anarrow c in FIG. 2.

With the above described disc cartridge, if the disc cartridge isinserted at the entrance opening in a mistaken direction, there arises arisk that those portions of the cartridge body 102 not provided with theaperture 103 be abutted by a magnetic device or an optical head deviceprovided in the disc recording and/or reproducing apparatus, possiblycausing injuries or destruction of the magnetic device, optical headdevice or the cartridge body 102.

With a conventional disc cartridge, the length of a side of thecartridge body 102 parallel to its inserting direction shown by arrow ain FIG. 1, that is the side corresponding to a lateral side of thecartridge body 102, is selected to be longer than that of a side thereofnormal to the inserting direction shown by arrow b in FIG. 1, that is aside corresponding to the forward side of the cartridge body 102. Insuch case, the mistaken operation of introducing the cartridge body 102into the entrance opening in a direction normal to the proper insertingdirection may be prevented by selecting the length of the entranceopening to be approximately equal to the length of the side of thecartridge body 102 normal to the proper inserting direction.

However, with such disc cartridge, since it is necessary to select thelengths of the lateral sides of the cartridge body 102 as describedabove, it becomes necessary to increase the size of the cartridge bodybeyond the minimum size required for accommodating the disc 101.

On the other hand, even if the length of the lateral side of thecartridge body 102 is selected to differ from that of its forward side,it is impossible to prevent mistaken inserting operations of insertingthe disc cartridge at the entrance opening with the rear side of thecartridge body as the leading end or of inserting the disc cartridgebody in a topsy-turvied position.

It may be envisaged to provide first and second mistaken insertioninhibiting grooves 111, 113 on the lateral sides of the cartridge body102, as shown in FIGS. 3 and 4, thereby preventing the disc cartridgefrom being introduced in the direction normal to the proper insertingdirection without the necessity of enlarging the length of the lateralside of the cartridge body 102 shown by arrow a in FIG. 4. The firstmistaken insertion inhibiting groove 111 is formed on the bottom surfaceof the cartridge body 102 for extending from the forward side towardsthe rear side of the cartridge body 102 when looking in its insertingdirection shown by arrow d in FIG. 4. The second mistaken insertioninhibiting groove 113 is formed on the lateral side of the cartridgebody 102 for extending from the leading side towards the trailing sideof the cartridge body 102 when looking in its inserting direction shownby arrow d in FIG. 4. The distance between the grooves 111 and 113,indicated by double-headed arrow b in FIG. 4, is selected to be shorterthan the length of the lateral side of the cartridge body 102 shown bydouble-headed arrow A in FIG. 4. In this manner, if lugs or the likemating with these grooves 111, 113 are provided in the vicinity of theentrance opening provided in the disc recording and/or reproducingapparatus, the cartridge body 102 may be positively prevented from beingintroduced into the entrance opening in the direction normal to itsproper inserting direction.

However, there are occasions wherein indicating holes or grooves areformed on the outer lateral side of the cartridge body 102 forindicating disc types, such as a disc in which information signals maybe recorded and reproduced, e.g. a magneto-optical disc, a disc in whichinformation signals may be recorded and reproduced but in whichinformation signals, once recorded, can not be erased, or a disc inwhich information signals can only be reproduced, e.g. an optical disc.With the above described disc recording and/or reproducing apparatus, itis necessary to adjust or switch the intensities of the magnetic fieldproduced by the magnetic head as an external magnetic field generatingdevice, operating or non-operating states or the light output of theoptical pickup device, depending on the disc types. For this reason,microswitches or the like are provided in the disc recording and/orreproducing apparatus for detecting the presence or absence of theseindicating holes or grooves for performing the adjusting or switchingoperations.

If the mistaken insertion preventing grooves are provided in thecartridge body already provided with these indicating holes or grooves,there arises a risk that the cartridge body becomes inferior inmechanical strength such that the disc 101 can not be protectedpositively. On the other hand, if the mistaken insertion inhibitinggrooves are provided in the cartridge body, the area on the lateral sidethereof to be reserved for the indicating holes or grooves becomesnarrow so that the disc cartridge needs to be enlarged in size forproviding these indicating holes or grooves.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide a disc cartridgewhich can be prevented from being introduced into the recording and/orreproducing apparatus in a mistaken or incorrect manner withoutenlarging the size of the disc cartridge or without lowering itsmechanical strength.

It is another object of the present invention to provide a disccartridge in which the mistaken insertion inhibiting grooves may be usedfor discriminating the disc types.

In accordance with the present invention, there is provided a disccartridge comprising a cartridge body having an aperture for exposing atleast a part of a signal recording area of a disc accommodated therein,a shutter slidably mounted on said cartridge body for opening andclosing said aperture, a shutter opening groove formed in the cartridgebody for extending along the sliding direction of the shutter which isparallel to the direction of insertion of the disc cartridge into arecording and/or reproducing apparatus adapted for recording and/orreproducing information signals on or from the disc, and a mistakeninsertion inhibiting groove formed in the cartridge body for extendingparallel to the shutter opening groove, the mistaken insertioninhibiting groove being shorter in length than the shutter openinggroove.

The mistaken insertion inhibiting groove is also divided into aplurality of regions of different depths.

Since the disc cartridge is formed with a mistaken insertion inhibitinggroove extending parallel to and shorter in length than the shutteropening groove, so that, by providing detection pins or the like meansin the recording and/or reproducing apparatus in association with thegrooves, it becomes possible to prevent the mistaken inserting operationof inserting the disc cartridge from a mistaken inserting direction.

Since the mistaken insertion inhibiting groove is shorter in length thanthe shutter opening groove, there is no necesity of enlarging the sizeof the disc cartridge for the sake of providing the mistaken insertioninhibiting groove.

If the mistaken insertion inhibiting groove is divided into a pluralityof regions of different depths, it becomes possible to discriminate thetype of the disc accommodated in the disc cartridge.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a conventional disc cartridge.

FIG. 2 is a plan view showing the disc cartridge shown in FIG. 1, with ashutter member closing an aperture in the cartridge body.

FIG. 3 is a side view, as viewed from the front side, showing aconventional disc cartridge provided with disc type indicating grooves.

FIG. 4 is a plan view showing the conventional disc cartridge shown inFIG. 3.

FIG. 5 is an exploded perspective view showing a disc cartridgeaccording to the present invention.

FIG. 6 is a plan view showing a disc cartridge according to anembodiment of the present invention.

FIG. 7 is a plan view showing the disc cartridge shown in FIG. 6, with ashutter member closing a recording/reproducing aperture.

FIG. 8 is a side view, as viewed from the forward side, showing the disccartridge shown in FIG. 6.

FIG. 9 is a plan view showing a disc cartridge according to a modifiedembodiment of the present invention.

FIG. 10 is a side view, as viewed from the forward side, showing thedisc cartridge shown in FIG. 9.

FIG. 11 is a side view, as seen from the forward side, showing a disccartridge according to another modified embodiment of the presentinvention.

FIG. 12 is a plan view showing the disc cartridge shown FIG. 11.

FIG. 13 is an enlarged perspective view showing the mistaken insertioninhibiting groove in the disc cartridge shown in FIG. 11.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, preferred embodiments of the presentinvention will be explained in detail.

In these embodiments, the present invention is applied to a disccartridge in which a disc accommodated therein is an optical disc forrecording and/or reproducing information signals to use a laser beamradiated from a recording and/or reproducing apparatus.

Referring first to FIG. 5, the disc cartridge includes a disc 1 and acartridge body 2 for accommodating the disc 1. The disc 1, accommodatedin the cartridge body 2, is a so-called optical disc in which arecording layer is formed by depositing and molding an optical recordingmaterial or a light reflective material on a base plate formed of alight-transmitting synthetic resin or glass. The disc 1 is formed with acentral disc hub 3 by means of which the disc may be clamped withrespect to a disc rotating device, not shown, provided within the discrecording and/or reproducing apparatus adapted for recording and/orreproducing information signals on or from the recording layer.

The disc hub 3 is disc-shaped and formed of a magnetic material, such asmetal. The portion of the disc 1 lying around the disc hub 3 representsa signal recording area for recording and/or reproducing informationsignals with the aid of the disc recording and/or reproducing apparatus.

On the other hand, the cartridge body 2 is made up of an upper half 4and a mating lower half 5 of synthetic resin which are abutted andconnected to each other such as by ultrasonic welding, adhesive or withset screws, in the form of a thin-walled substantially square-shapedcasing. That is, each of upper and lower major surfaces 4a and 5a of thecartridge body 2 extending parallel to the major surface of the disc 1is in the form of a square each side of which is slightly shorter thanthe disc diameter. The distance between the major surfaces 4a and 5a,that is the thickness of the cartridge body 2, is slightly thicker thanthe thickness of the disc hub 3.

The major surfaces 4a and 5a of the cartridge body 2 are formed with anupper recording/reproducing aperture 6 and a lower recording/reproducingaperture 7, respectively, which are in register with each other. Theserecording/reproducing apertures 6 and 7 are rectangular in profile andextended from near the center of the major surfaces 4a and 5a to closeto one sides of the surfaces 4a and 5a, respectively, that is, to closeto a lateral side of the cartridge body, so as to be in register witheach other with the disc 1 in-between. The upper aperture 6 is adaptedfor exposing a portion of the signal recording surface of the disc 1directed towards the upper half 4 to outside across the inner and outerperipheries of the disc. On the other hand, the lower aperture 7 isadapted for exposing a portion of the signal recording surface of thedisc 1 directed towards the lower half 5 to outside across the inner andouter peripheries of the disc. The recording and/or reproducing deviceof the disc recording and/or reproducing apparatus, such as an opticalhead device, is introduced via these apertures 6 and 7 into thecartridge body 2 for recording and/or reproducing information signals onor from the disc 1.

Meanwhile, if the disc 1 accommodated within the cartridge body 2 is amagneto-optical disc, an external magnetic field generating device forsupplying the external magnetic field to the disc needs to be providedin the disc recording and/or reproducing apparatus in addition to theoptical head device.

The major surface of the lower half 5 is formed with a circular chuckingaperture 8 for permitting the lower surface of the disc hub 3 to beexposed to outside. It is by means of this chucking aperture 8 that achucking device of disc rotating means of the disc recording and/orreproducing apparatus, such as a disc table, is introduced into thecartridge body 2 for chucking the disc 1.

A shutter member 9 for opening or closing the recording/reproducingapertures 6 and 7 is mounted on the cartridge body 2, as shown in FIGS.5 and 6. The shutter member 9 is comprised of a slide portion 10,supported by a lateral side of the cartridge body 2, and upper and lowershutter portions 11 and 12, and is formed integrally from a syntheticresin, such as polyacetal resin. The slide portion 10 is in the form ofan elongated plate having a width equal to the thickness of thecartridge body 2. The shutter portions 11 and 12 are in the form ofrectangles larger in size than the recording/reproducing apertures 6 and7 for closing the apertures 6 and 7 and are of a predetermined thicknessof an order of, for example, 0.3 min. When seen in cross-section, theshutter member 9 is in the form of a letter U having the slide portion10 as a web and the shutter portions 11 and 12 as both sides of theletter U, so that the shutter portions face each other with a gapin-between which corresponds to the thickness of the cartridge body 2.

The shutter portions 11 and 12 are formed with through-holes 13 and 14,respectively, which are substantially in register with therecording/reproducing apertures 6 and 7, respectively.

The inner lateral side of the shutter portion 10 directed to the distalfree ends of the shutter portions 11 and 12 is formed with engaginglugs, not shown, for engaging with supporting grooves 15, 15 provided inthe vicinity of a lateral side of the cartridge body 2. These supportinggrooves 15, 15 are defined between a pair of ribs provided in thevicinity of the aforementioned lateral side on the inner lateral sidesof the upper and lower halves 4 and 5 for extending parallel to eachother and to the aforementioned lateral side. This lateral side of thecartridge body 2 is formed with a slit 15a for extending along thesupporting grooves 15, 15.

The engaging lug of the slide portion 10 is introduced via the slit 15ainto the cartridge body 2 so that the slide portion 10 is supported withthe inner lateral side thereof abutted on the aforementioned lateralside of the cartridge body 2. Since the engaging lug may be slid alongthe supporting grooves 15, 15, the slide portion 10 may be slid alongthe aforementioned lateral side of the cartridge body 2.

By having its slide portion 10 supported by the lateral side of thecartridge body 2, the shutter member 9 is supported by the cartridgebody 2, with the shutter portions 11 and 12 lying along the upper andlower major surfaces 4a and 5a, respectively. Also, by having its slideportion 10 slidable with respect to the cartridge body 2, the shuttermember 9 may be slid with respect to the cartridge body 2, as shown byarrows J and K in FIG. 5, so that the shutter portions 11 and 12 aremoved along the upper and lower major surfaces 4a and 5a, respectively.

With the shutter member 9 sliding in this manner with respect to thecartridge body 2, the upper shutter plate 11 may be slid between a firstposition of closing the upper recording/reproducing aperture 6, with theaperture 6 then being out of register with the through-hole 13, as shownin FIG. 6, and a second position of opening the upperrecording/reproducing aperture 6, with the aperture 6 then being inregister with the through-hole 13, as shown in FIG. 7. Similarly, withthe shutter member 9 sliding with respect to the cartridge body 2, thelower shutter plate 11 may be slid between a first position of closingthe lower recording/reproducing aperture 7, with the aperture 7 thenbeing out of register with the through-hole 14, and a second position ofopening the lower recording/reproducing aperture 7, with the aperture 7then being in register with the through-hole 14. These first and secondpositions are so oriented relative to each other that the direction fromthe second to the first position corresponds to the inserting directionof the disc cartridge into the disc recording and/or reproducingapparatus as shown by arrow L in FIGS. 5 and 6.

First and second shutter guide recesses 16 and 17 are formed in theportion of the major surfaces 4a and 5a of the cartridge body 2corresponding to the travel passage of the shutter portions 11 and 12 ofthe shutter member 9. The first shutter guide recess 16 in the uppermajor surface 4a is formed in an area to be traversed by the uppershutter portion 11 as it is moved from the first position to the secondposition, and is of a depth from the upper major surface 4a of the orderof, for example, 0.3 mm, corresponding to the thickness of the uppershutter portion 11 . In this manner, the upper surface of the uppershutter portion 11 is substantially flush with the upper surface 4athroughout the stroke of movement of the shutter member 9 between theaforementioned first and second positions.

The second shutter guide recess 17 in the upper major surface 5a isformed in an area to be traversed by the lower shutter portion 12 as itis moved from the first position to the second position, and is of adepth from the lower major surface 5a of the order of, for example, 0.3mm, corresponding to the thickness of the lower shutter portion 12. Inthis manner, the upper surface of the upper shutter portion 12 issubstantially flush with the lower surface 5a throughout the stroke ofmovement of the shutter member 9 between the aforementioned first andsecond positions.

The lateral sides of the cartridge body 2 are formed with a shutteropening groove 18 and a mistaken insertion inhibiting groove 19, asshown in FIGS. 5 to 8.

The shutter opening groove 18 is formed on a lateral side of thecartridge body 2 along the direction of insertion of the disc cartridgeinto the disc recording and/or reproducing apparatus shown by arrow L inFIG. 6, that is along the sliding direction of the shutter member 9. Theshutter opening groove 18 has a length F_(L) between the leading edge ofthe cartridge body 2 in the inserting direction of the disc cartridgeinto the disc recording and/or reproducing apparatus and the leadingedge of the slide portion 10 of the shutter member 9 when the shuttermember is at the second position of opening the recording/reproducingapertures 6 and 7, as indicated by arrow F in FIG. 7.

The mistaken insertion inhibiting groove 19 is formed in the lateralside of the cartridge body 2 opposite to the lateral side thereofprovided with the shutter opening groove 18, and is extended in adirection parallel to the shutter opening groove 18. The mistakeninsertion inhibiting groove 19 has a length G_(L) from the leading edgeof the cartridge body which is shorter than the length of the shutteropening groove 18, as indicated by arrow G in FIG. 7. That is, thelengths F_(L) and G_(L) are related to each other by an inequality

    G.sub.L <F.sub.L                                           (1)

With the above described cartridge body 2, a length B_(L) from thebottom of the shutter opening groove 18 to the bottom of the mistakeninsertion inhibiting groove 19 as indicated by arrow B in FIG. 6 isselected to be shorter than a length A_(L) of the side of the cartridgebody 2 along the inserting direction. on the other hand, the lengthB_(L) is selected to be shorter than a length C_(L) of the side of thecartridge body 2 normal to the inserting direction, as indicated byarrow C in FIG. 6. That is, these lengths are related to one another byinequalities

    B.sub.L <A.sub.L                                           (2)

    B.sub.L <C.sub.L                                           (3)

On the other hand, with the above described cartridge body 2, a lengthH_(L) from the upper sidewall portion of the mistaken insertioninhibiting groove 19 to the upper major surface 4a as shown by arrow Hin FIG. 8 is different from a length I_(L) from the lower sidewallsection of the mistaken insertion inhibiting groove 19 to the lowermajor surface 5a as indicated by arrow I in FIG. 8. That is, theselengths are related to each other by

    H.sub.L ≠I.sub.L                                     (4)

so that the mistaken insertion inhibiting groove 19 is slightly offsetin a direction along the thickness of the cartridge body 2.

With the above described disc cartridge of the present invention, theshutter portions 11 and 12 of the shutter member 9 are in the firstposition of closing the recording/reproducing apertures 6 and 7, whenthe disc cartridge is not in use, for preventing intrusion of dust anddirt or the user's finger into the cartridge body 2 by means of therecording/reproducing apertures 6 and 7.

When the disc cartridge is in use, it is loaded in a cartridge loadingunit 51 of the disc recording and/or reproducing apparatus, as shown inFIG. 7. A cartridge entrance opening 51a, providing an entrance to thecartridge loading unit 51, has a width slightly larger than thethickness of the cartridge body 2 and a length E_(L) slightly largerthan the length C_(L) of the disc cartridge 2 in the direction normal toits inserting direction shown by arrow C in FIG. 6, as indicated byarrow E in FIG. 7. That is, these lengths are related to each other byan inequality

    C.sub.L <E.sub.L                                           (5)

The disc cartridge is introduced into the cartridge loading unit 51, bymeans of the cartridge entrance opening 51a, with the side of thecartridge body normal to the shutter member side thereof as the leadinginserting side.

A shutter opening pin 52 is provided upright on an inner wall of thecartridge loading unit 51 facing the side of the cartridge body providedwith the shutter opening groove 18. A mistaken insertion inhibiting pin53 is provided upright on an inner wall of the cartridge loading unit 51corresponding to the side of the cartridge body provided with themistaken insertion inhibiting groove 19.

The distance D_(L) between the foremost parts of these pins 52 and 53 asshown by arrow D in FIG. 7 is selected to be slightly longer than thelength B_(L) between the bottom of the shutter opening groove 18 and thebottom of the mistaken insertion inhibiting groove 19 as indicated byarrow B in FIG. 6. On the other hand, the distance D_(L) is selected tobe shorter than the length C_(L) along the inserting direction of thedisc cartridge. In addition, the distance D_(L) is selected to beshorter than the length A_(L) along the inserting direction of the disccartridge 1. That is, the above lengths are related to one another byinequalities

    B.sub.L <D.sub.L                                           (6)

    D.sub.L <C.sub.L                                           (7)

    D.sub.L <A.sub.L                                           (8)

Referring to FIG. 7, the shutter opening pin 52 is positioned so that,when the disc cartridge is kept in position within the cartridge loadingunit 51, the pin 52 is spaced apart from the leading edge of thecartridge body 2 by a distance corresponding to the length F_(L) of theshutter opening groove 18 shown by arrow F in FIG. 7. On the other hand,the mistaken insertion inhibiting pin 53 is positioned so that, when thedisc cartridge is kept in position within the cartridge loading unit 51,the pin 53 is spaced apart from the leading edge of the cartridge body 2by a distance corresponding to the length G_(L) of the mistakeninsertion inhibiting groove 19 shown by arrow G in FIG. 7. The mistakeninsertion inhibiting pin 53 is slightly offset along the direction ofthickness of the cartridge body 2 for mating with the mistaken insertioninhibiting groove 19.

Meanwhile, when the disc cartridge is introduced by means of theentrance opening 51a halfway in the cartridge loading unit 51, theshutter opening pin 52 is intruded into the shutter opening groove 18.The slide portion 10 of the shutter member 9 is abutted against theshutter opening pin 52. When the disc cartridge is introduced into theinterior of the cartridge loading unit 51, the shutter member 9 is leftat a position in which the slide portion 10 is abutted against theshutter opening pin 52. Thus the shutter member 9 is slid from theposition of closing the apertures 6 and 7 by its shutter portions 11 and12 towards the position of opening the apertures by the shutterportions.

When the disc cartridge is further introduced into the interior of thecartridge loading unit 51, the mistaken insertion inhibiting pin 53 isintruded into the inside of the mistaken insertion inhibiting groove 19.The shutter member 9 is further slid for bringing the shutter portions11 and 12 to the position of opening the recording/reproducing apertures6 and 7 for opening these recording/reproducing apertures. At this time,information signals may be recorded of reproduced on or from the disc 1by means of the recording/reproducing apertures 6 and 7.

With the above described disc cartridge, from the formulas (3), (5) and(7), the following inequality

    B.sub.L <D.sub.L <C.sub.L <E.sub.L                         (9)

holds. Therefore, even if the mistaken inserting operation of insertingthe disc cartridge from its fear side first into the cartridge loadingunit 51 by means of the cartridge entrance opening 51a should beperformed, the disc cartridge is abutted against the mistaken insertioninhibiting pin 53 and thereby prevented from being introduced furtherinto the interior of the cartridge loading unit 51.

On the other hand, from the formulas (2), (6) and (8), the followinginequality

B_(L) <D_(L) <A_(L) (10)

holds. Therefore, even if the mistaken inserting operation of insertingthe disc cartridge into the cartridge loading unit 51 by means of thecartridge entrance opening 51a from the direction normal to the correctinserting direction should be performed, the disc cartridge is abuttedagainst the mistaken insertion inhibiting pin 53 and thereby preventedfrom being introduced further into the interior of the cartridge loadingunit 51.

In addition, with the present disc cartridge, the mistaken insertioninhibiting groove 19 is shorter in length than the shutter openinggroove 18, and is offset along the thickness of the cartridge body 2.Therefore, even if the mistaken inserting operation of inserting thedisc cartridge into the cartridge loading unit 51 in a topsy-turviedposition should be performed, the disc cartridge is abutted against themistaken insertion inhibiting pin 53 and thereby prevented from beingintroduced further into the interior of the cartridge loading unit 51.

Besides, with the present disc cartridge, the mistaken insertioninhibiting groove 19 is shorter in length than the shutter openinggroove 18. Therefore, the present disc cartridge need not be enlarged insize beyond the size of the disc accommodated therein for the sake ofproviding the mistaken insertion inhibiting groove 19, so that the disccartridge may be reduced in size.

The disc cartridge of the present invention may also be so constructedthat, as shown in FIGS. 9 and 10, the mistaken insertion inhibitinggroove 19 is provided in the upper major surface 4a or in the lowermajor surface 5a. With the disc cartridge shown in FIGS. 9 and 10, themistaken insertion inhibiting groove 19 is provided in the lower majorsurface 5a. The mistaken insertion inhibiting groove 19 is shorter inlength than the shutter opening groove 18, as in the above describedembodiment. The mistaken insertion inhibiting groove 19 is so designedthat the length B_(L) from the bottom of the shutter opening groove 18to the sidewall of the mistaken insertion inhibiting groove 19 along theone lateral side of the cartridge body 2 as indicated by arrow B inFIGS. 9 and 10 is shorter than the length C_(L) of the cartridge body 2along the direction normal to the inserting direction of the disccartridge shown by arrow C in FIGS. 9 and 10. On the other hand, thelength B_(L) is selected to be shorter than the length A_(L) of thecartridge body 2 along its inserting direction as indicated by arrow Ain FIG. 9.

With the above described disc cartridge, by providing the mistakeninsertion inhibiting pin within the cartridge loading unit 51 of thedisc recording and/or reproducing apparatus 50 for mating with themistaken insertion inhibiting groove 19, the mistaken insertingoperation of inserting the disc cartridge in an inserting directiondifferent from the correct inserting direction may be inhibited withoutenlarging the size of the cartridge body 2.

The disc cartridge of the present invention may also be so constructedthat, as shown in FIGS. 11 to 13, the mistaken insertion inhibitinggroove 19 has a plurality of regions 19a, 19b of different depths fromthe lower major surface 5a. Meanwhile, the disc 1 accommodated withinthe disc cartridge shown in FIGS. 11 to 13 is a so-calledmagneto-optical disc or an optical disc. In FIGS. 11 to 13, the shuttermember for opening or closing the recording/reproducing aperture 7 forexposing the disc 1 to outside is not shown for clarity.

The cartridge body 2 of the present disc cartridge comprised of an upperhalf 4 and a lower half 5 abutted and connected to each other, similarlyto the cartridge body 2 of the preceding embodiments. The lower majorsurface 5a of the cartridge body 2 is provided with a central chuckingopening 8 by means of which the lower surface of the disc hub 3 providedat the center of the disc 1 is exposed to outside.

This cartridge body 2 is introduced into the disc recording and/orreproducing apparatus with the direction shown by arrow L in FIG. 12 asthe inserting direction. With the present disc cartridge, the lengthB_(L) from its one lateral side to a lateral side of the mistakeninsertion inhibiting groove 19 as indicated by arrow B in FIG. 12 isselected to be shorter than the length A_(L) along the insertingdirection of the cartridge body 2 shown by arrow A in FIG. 12. On theother hand, with the present disc cartridge, the length B_(L) from itslateral side to the lateral side of the mistaken insertion inhibitinggroove 19 is selected to be shorter than the length C_(L) along thedirection normal to the inserting direction of the cartridge body 2shown by arrow C in FIG. 12. That is, the above mentioned formulas (2)and (3) hold with the cartridge body 2 of the present disc cartridge.

Thus, with the present disc cartridge, by providing the mistakeninsertion inhibiting pin within the cartridge loading unit 51 of thedisc recording and/or reproducing apparatus for mating with the mistakeninsertion inhibiting groove 19, the mistaken inserting operation ofinserting the disc cartridge into the cartridge loading unit 51 from thedirection different from the correct inserting direction may beinhibited without enlarging the size of the cartridge body 2.

The mistaken insertion inhibiting groove 19 in the cartridge body 2 ofthe disc cartridge is formed with first and second regions 19a, 19b ofdifferent depths from the lower major surface 5a. The first region 19ais situated towards the forward side of the cartridge body 2 within themistaken insertion inhibiting groove 19, while the second region 19b issituated towards the rear of the first region 19a within the mistakeninsertion inhibiting groove 19.

The depth of the second region 19b of the mistaken insertion inhibitinggroove 19 from the lower major surface 5a is substantially equal to thedepth of the mistaken insertion inhibiting groove 19 in the disccartridge shown in FIGS. 9 and 10. The depth of the first region 19a ofthe mistaken insertion inhibiting groove 19 is different from the depthof the second region 19b and associated with the type of the discaccommodated in the disc cartridge. By way of illustrating the variousdisc types, the disc 1 may be a magneto-optical disc in whichinformation signals can be recorded and reproduced, or a so-calledrewritable disc in which information signals can be recorded andreproduced. The disc 1 may also be a so-called rewritable disc in whichthe information signals, once recorded by the user, can not be erased,that is a disc in which recording may be made only once. The disc 1 mayalternatively be an optical disc in which information signals may onlybe reproduced, that is a so-called read-only disc. Thus the first region19a of the mistaken insertion inhibiting groove 19 may be used as anindicating groove for indicating the type of the disc 1.

That is, with the disc recording and/or reproducing apparatus, makinguse of the above described disc cartridge, when the disc cartridge isinserted in position within the cartridge loading unit, the mistakeninsertion inhibiting pin is intruded into the second region 19b of themistaken insertion inhibiting groove 19, that is to close to the rearend of the mistaken insertion inhibiting groove 19. With the presentdisc recording and/or reproducing apparatus, the depth of the mistakeninsertion inhibiting groove 19 in the first region 19a is sensed by adisc type sensor constituted by microswitch(es) or link(s). With thepresent disc recording and/or reproducing apparatus, the type of thedisc 1 is discriminated on the basis of the depth of the mistakeninsertion inhibiting groove 19 in the first region 19b, and theintensities of the magnetic field generated by the magnetic head devicefor signal writing, the state of operation or non-operation or the lightoutput generated by the optical head device, may be adjusted or switcheddepending on the discriminated disc type.

Meanwhile, if the depths from the lower major surface 5a of the firstand second regions 19a, 19b of the mistaken insertion inhibiting groove19 are selected to be equal to each other, the present disc cartridge issimilar in construction to the disc cartridge shown in FIGS. 9 and 10.In such case, the first region 19a of the mistaken insertion inhibitinggroove 19 may still be used as an indicating groove for indicating thedisc type. It is noted that the first region 19a of the mistakeninsertion inhibiting groove 19 may be of the same thickness as thecartridge body 2, that is, the first region 19a of the groove 19 may beformed as a through-slot extending from the lower major surface 5a tothe upper major surface 4a.

When the mistaken insertion inhibiting groove 19 is divided into aplurality of regions, the number of the regions may be three or moreinstead of being limited to two, as in the preceding embodiment. Thegroove 19 may also be divided in the transverse direction with respectto the inserting direction of the disc cartridge into the discrecording/reproducing apparatus, instead of in the fore and aftdirection with respect to the inserting direction, as in the aboveembodiment.

It is noted that the mistaken insertion inhibiting groove 19 provided inthe lateral side of the cartridge body 2 as shown in FIGS. 6 to 8 mayalso be divided into a plurality of regions of different depths.

Meanwhile, the present invention is not limited to a disc cartridge inboth major surfaces of which the recording/reproducing apertures 6 and 7are formed, as in the preceding embodiments. That is, the present disccartridge may also be provided with a recording/reproducing aperture inonly one of the major surfaces of the disc cartridge. In such case, theshutter member 9 is provided only with a shutter portion associated withthe recording/reproducing aperture.

The present invention also is not limited to a disc cartridge for anoptical of magneto-optical disc as shown in the preceding embodiments,but may equally be applied to other recording media for other systems,such as a flexible magnetic disc.

What is claimed is:
 1. A disc cartridge comprising:a cartridge bodyhaving a thickness and an aperture for exposing at least a part of asignal recording area of a disc accommodated therein; a shutter slidablymounted on said cartridge body for opening and closing said aperture,the shutter being slidable in a recess formed in a pair of opposing,parallel, lateral faces of the cartridge body; a shutter opening grooveformed in a first lateral side of said cartridge body and extendingalong a sliding direction of said shutter which is parallel to thedirection of insertion of the disc cartridge into a recording and/orreproducing apparatus; a mistaken insertion inhibiting groove formed ina second lateral side of said cartridge body and extending parallel tosaid shutter opening groove, and said mistaken insertion inhibitinggroove being shorter in length than the length of said shutter openinggroove; wherein said shutter opening groove and the mistaken insertioninhibiting groove are both opened on a third lateral side of saidcartridge body which is a leading lateral side in the direction ofinsertion of the disc cartridge into the recording and/or reproducingapparatus; and wherein the length (G) of the mistaken insertioninhibiting groove and a length (F) along the direction of the shutteropening groove to a leading edge of the shutter when the shutter is inan open position are taken in directions parallel to the shutter slidingdirection and the length (G) of the mistaken insertion inhibiting grooveis less than the length (F) along the direction of the shutter openinggroove to the leading edge of the shutter when the shutter is in theopen position.